Novel phenol stabilizers

ABSTRACT

Phenols of the formula I ##STR1## wherein N HAS A VALUE FROM 1 TO 15, 
     Each of R 1 , R 2 , R 3  and R 4  independently is a hydrogen atom, a C 1  -C 18  -alkyl group, an aryl group, a C 5  -C 12  -cyclo-alkyl group or a C 7  -C 13  -aralkyl group, 
     R 5  is a hydrogen atom or a C 1  -C 18  -alkyl group, 
     Y is a carbonyl, thiocarbonyl, sulphinyl, sulphonyl, --P(OR 7 )--P(═O)(OR 7 )--, --P(═O)(R 7 )-- or --P(R 7 )-- group, and R 6  is a radical --CHR 8  --CHR 9  --S--CR 10  R 11  R 12 , wherein each of R 8  and R 9  independently is a hydrogen atom or a C 1  -C 6  -alkyl group, R 10  is a hydrogen atom, a C 1  -C 19  -alkyl group, a C 2  -C 4  -alkenyl group or an aryl group, R 11  is a hydrogen atom or a methyl group and R 12  is a hydrogen atom or a methyl group, or, if R 11  is a hydrogen atom, is a C 2  -C 6  -alkyl group, or, if R 10  is a hydrogen atom, R 11  and R 12  together with the carbon atom to which they are attached represent a cycloalkyl group, or R 10 , R 11  and R 12  together with the carbon atom to which they are attached represent an aryl group, or if Y is a thiocarbonyl, sulphinyl or sulphonyl group, 
     R 6  can also be a hydrogen atom or a C 1  -C 18  -alkyl group or an aryl group, and 
     R 7  is a hydrogen atom, a C 1  -C 18  -alkyl group or an aryl group, as stabilizers for organic material.

The invention relates to novel phenols which are suitable antioxidants,a process for their manufacture, and to the use thereof for stabilisingpolymers and organic material which are normally subject to oxidativedegradation.

Polycarbonates which are described as effective antioxidants forpolyolefins, such as polypropylene, are known from U.S. Pat. No.3,655,718 and also U.S. Pat. No. 3,510,507, which disclosessubstantially the same inventive subject matter, and from DT-OS No.2,016,296. Thus, for example, a polycarbonate of the formula ##STR2## isdescribed as an antioxidant for polyolefins in Example VB of U.S. Pat.No. 3,655,718. Similar compounds are also known from U.S. Pat. No.3,579,561.

These known polycarbonates are characterised by a methylene group whichis positioned between two phenyl radicals and which is unsubstituted orsubstituted by alkyl or aryl. Although these polycarbonates do have anantioxidative action in polyolefins, this action does not suffice foruse in actual practice.

Starting from this prior art, the present invention discloses novelphenols which have an excellent oxidative action when incorporated inpolymers, in particular in polyolefins. The novel phenols have theformula I ##STR3## wherein n has a value from 1 to 15,

each of R₁, R₂, R₃ and R₄ independently is a hydrogen atom, a C₁ -C₁₈-alkyl group, an aryl group, a C₅ -C₁₂ -cycloalkyl group or a C₇ -C₁₃-aralkyl group,

R₅ is a hydrogen atom or a C₁ -C₁₈ -alkyl group,

Y is a carbonyl, thiocarbonyl, sulphinyl, sulphonyl, --P(OR₇)--,--P(═O)(OR₇)--, --P(═O)(R₇)-- or --P(R₇)-- group, and

R₆ is a radical --CHR₈ --CHR₉ --S--CR₁₀ R₁₁ R₁₂, wherein each of R₈ andR₉ independently is a hydrogen atom or a C₁ -C₆ -alkyl group,

R₁₀ is a hydrogen atom, a C₁ -C₁₉ -alkyl group, a C₂ -C₄ -alkenyl groupor an aryl group,

R₁₁ is a hydrogen atom or a methyl group and

R₁₂ is a hydrogen atom or a methyl group, or, if R₁₁ is a hydrogen atom,is a C₂ -C₆ -alkyl group, or, if R₁₀ is a hydrogen atom, R₁₁ and R₁₂together with the carbon atom to which they are attached represent acycloalkyl group, or R₁₀, R₁₁ and R₁₂ together with the carbon atom towhich they are attached represent an aryl group, or if Y is athiocarbonyl, sulphinyl or sulphonyl group,

R₆ can also be a hydrogen atom or a C₁ -C₁₈ -alkyl group or an arylgroup, and

R₇ is a hydrogen atom, a C₁ -C₁₈ -alkyl group or an aryl group.

A C₁ -C₁₈ -alkyl group represented by R₁, R₂, R₃, R₄, R₅, R₆ or R₇ canbe a straight-chain or branched alkyl group, such as a methyl, ethyl,n-propyl, iso-propyl, n-butyl, sec.-butyl or tert.-butyl group, as wellas a branched or straight-chain pentyl, hexyl, n-octyl, tert.-octyl,decyl, dodecyl, tetradecyl, hexadecyl or octadecyl group.

An aryl group represented by R₁, R₂, R₃, R₄, R₆, R₇ or R₁₀ is inparticular a substituted or unsubstituted phenyl group, such as a phenylgroup which is unsubstituted or polysubstituted, or especiallymonosubstituted, by halogen, such as chlorine, alkyl, such as C₁ -C₆-alkyl, in particular methyl, and/or alkoxy, such as C₁ -C₆ -alkoxy, inparticular methoxy; preferably, however, an aryl group is anunsubstituted phenyl group.

A C₁ -C₆ -alkyl group represented by R₈ or R₉ is a branched or, inparticular, straight-chain alkyl group, such as an ethyl, n-propyl orpreferably methyl group.

An alkenyl group represented by R₁₀ is in particular an allyl, methallylor vinyl group.

A cycloalkyl group represented by R₁₁ and R₁₂ together with the carbonatom to which they are attached is in particular a cyclopentyl orcyclohexyl group. An aryl group represented by R₁₀, R₁₁ and R₁₂ togetherwith the carbon atom to which they are attached is in particular an arylgroup as defined above, in particular a phenyl group.

A C₁ -C₁₉ -alkyl group represented by R₁₀ is a branched, or inparticular straight-chain, alkyl group as defined for example for R₁,especially a n-butyl, n-octyl, n-dodecyl or n-octadecyl group.

A C₂ -C₆ -alkyl group represented by R₁₂ is a branched, or in particularstraight-chain, alkyl group, such as a n-propyl, n-butyl or especiallyethyl group.

Preferred phenols are the phenols Ia of the formula (I) wherein

n is 1 to 4,

R₁ is a hydrogen atom or a methyl group,

R₂ is a hydrogen atom, a methyl, ethyl or tert.-butyl group,

R₃ is a hydrogen atom, a methyl, ethyl or tert.-butyl group, each of

R₄ and R₅ is a hydrogen atom,

Y is a carbonyl, --P(OR₇)--, --P(═O)(OR₇)--, --P(═O)(R₇)-- or --P(R₇)--group,

R₆ is a radical --CHR₈ --CHR₉ --S--CR₁₀ R₁₁ R₁₂,

R₈ is a hydrogen atom,

R₉ is a hydrogen atom or a methyl group,

R₁₀ is a C₄ -C₁₉ -n-alkyl group, each of

R₁₁ and R₁₂ is a hydrogen atom, and

R₇ is a hydrogen atom, a C₁ -C₁₈ -alkyl group or a phenyl group.

Particularly preferred phenols are phenols Ib of the formula (I),wherein

n is 1 to 4,

R₁ is a hydrogen atom or a methyl group,

R₂ is a hydrogen atom, a methyl, ethyl, or tert.-butyl group,

R₃ is a hydrogen atom, a methyl, ethyl, or tert.-butyl group,

each of R₄ and R₅ is a hydrogen atom,

Y is a carbonyl, --P(OR₇)-- or --P(═O)(OR₇)-- group,

R₆ is a radical --CHR₈ --CHR₉ --S--CR₁₀ R₁₁ R₁₂,

R₈ is a hydrogen atom,

R₉ is a hydrogen atom or a methyl group,

R₁₀ is a C₄ -C₁₈ -n-alkyl or phenyl group, each of

R₁₁ and R₁₂ is a hydrogen atom, and

R₇ is a C₁ -C₁₈ -n-alkyl or phenyl group.

The most preferred phenols are the phenols Ic of the formula (I) wherein

n is 1 or 4,

R₁ is a methyl group,

each of R₂, R₄ and R₅ is a hydrogen atom,

R₃ is a tert.-butyl group,

Y is a carbonyl or --P(O-phenyl)-group,

R₆ is a radical --CH₂ --CHR₉ -S-CH₂ R₁₀,

R₉ is a methyl group, and

R₁₀ is a C₄ -C₁₂ -n-alkyl group, and most preferably the phenolsillustrated in the Examples.

In the preferred phenols, Y is likewise sulphinyl or thiocarbonyl.

The novel phenols of the formula (I) can be obtained in a manner knownper se, for example by reacting a phenol of the formula (II) ##STR4##with an acid Y(OH)₂ or a reactive derivative thereof, wherein all thesymbols are as defined above.

In the above reaction, a reactive derivative of an acid Y(OH)₂, such asan acid halide, in particular an acid chloride, or an ester, such as analkyl or aryl ester, is preferably used. Depending on the definition ofY, examples of suitable acid halides and esters which can be used are:phosgene or a carbonate, such as diphenyl carbonate (Y= carbonyl),thiophosgene (Y= thiocarbonyl), thionyl chloride (Y= thiocarbonyl),thionyl chloride (Y= sulphinyl), sulphuryl chloride (Y= sulphonyl), R₇O--PCl₂ or P(OR₇)₃ (Y=--P(OR₇)--), R₇ O--P(═O)Cl₂ or --P(═O)(OR₇)₃ (Y=--P(═O) (OR₇)--), R₇ --P(═O)Cl₂ or R₇ --P(═O)(OR₇)₂ (Y= --P(═O)(R₇)--),R₇ --PCl₂ or R₇ --P(OR₇)₂ (Y= --P(R₇)--). For both acid halides andesters it is advantageous to use a catalyst, in particular a basiccatalyst. If the starting material is an acid halide, the catalyst isfor example an organic nitrogen base, such as pyridine or triethylamine,and if it is an ester, the catalyst is a strong base, such as a metalalcoholate, for example potassium tert.-butylate or lithium amide or thelike. It is advantageous to apply heat during the reaction: gentleheating if an acid halide is used and stronger heating if an ester isused, for example the reflux temperature of a solvent employed, such asan aprotic solvent, e.g. an ether, for example tetrahydrofuran ordioxan, or a hydrocarbon, such as toluene or xylene. The basic catalystcan also be used with advantage in equimolar amounts in order to bindthe hydrogen halide if the starting material is an acid halide. If anester is used as starting material, such as a phenyl ester, then thealcohol which forms, for example phenol, can be distilled off, ifappropriate until such time as no further distillate passes over.Temperatures of approx. 160° to 250° C. are suitable.

The phenols of the formula (II) are known, for example from U.S. Pat.No. 3,506,716. The acids Y(OH)₂ and their reactive derivatives are alsoknown.

According to the present invention, the compounds of the formula I canbe used as stabilisers for organic substrates. Suitable substrates arein particular polymers which are derived from hydrocarbons having singleor double unsaturation, such as polyolefins, for example polyethylenewhich may be crosslinked or uncrosslinked, polypropylene,polyisobutylene, polymethylbutene-1, polymethylpentene-1, polybutene-1,polyisoprene, polybutadiene, polystyrene, polyisobutylene, copolymers ofthe monomers based on the cited homopolymers, such as ethylene-propylenecopolymers, propylene-butene-1 copolymers, propylene-isobutylenecopolymers, styrene-butadiene copolymers, as well as terpolymers ofethylene and propylene with a diene, for example hexadiene,dicyclopentadiene or ethylenenorbornenes; mixtures of the abovementioned homopolymers, for example mixtures of polypropylene andpolyethylene, polypropylene and polybutene-1, polypropylene andpolyisobutylene.

Polymers which contain double bonds are also suitable, for example:polymers which are derived from hydrocarbons having double unsaturation,for example polyisopropylene or polybutadiene, polystyrene, copolymersof styrene or α-methylstyrene with dienes or acrylic derivatives, forexample styrene-butadiene, styrene-acrylonitrile,styrene-acrylonitrile-methacrylate; mixtures of high impact strengthconsisting of styrene copolymers and another polymer, for example apolyacrylate, a diene polymer or an ethylene-propylene-diene terpolymer;as well as block copolymers of styrene, for examplestyrene-butadiene-styrene; styrene-isoprene-styrene orstyrene-ethylene/butylene-styrene; graft copolymers of styrene, forexample styrene to polybutadiene, styrene and acrylonitrile topolybutadiene, and the mixtures thereof with the copolymers previouslymentioned, i.e. those known as ABS polymers.

Oils, such as lubricating oils and hydraulic fluids, are also suitable.

The compounds of the formula I are incorporated in the substrates as arule in a concentration of 0.01 to 5% by weight, based on the materialto be stabilised. Preferably 0.05 to 2%, most preferably 0.1 to 1% byweight of the compounds, based on the material to be stabilised, areincorporated thereinto. The incorporation can be accomplished forexample by blending in at least one of the compounds of the formula Iand optionally further additives by methods which are commonly employedin the art, before or during the forming, or also by applying solutionsor dispersions of the compounds to the polymers, if appropriate aftersubsequent evaporation of the solvent.

If the substrate is crosslinked polyethylene, the compounds of theformula I are advantageously added before the crosslinking. Thecompounds of the formula I can also be added before or during thepolymerisation.

Examples of further additives together with which the stabilisers can beused are: antioxidants, UV absorbers, light stabilisers, phosphites,compounds which decompose peroxide, basic costabilisers, nucleatingagents and other customary additives.

The following Examples illustrate the invention in more detail. Partsand percentages are by weight.

EXAMPLE 1

While scavenging with nitrogen, 1.7 ml (0.0034 mole) of a 20% solutionof phosgene in toluene are added dropwise over the course of 20 minutesto a mixture of 4.5 parts (0.0067 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-3-n-octadecylthiopropane.During the addition, the temperature rises from 20° to 29° C. Thereaction mixture is stirred for 2 hours at room temperature and thepyridine hydrochloride is subsequently removed by filtration. Thefiltrate is washed neutral with water, the toluene phase is dried oversodium sulphate and the toluene is stripped off in vacuo to give thedesired carbonate as an amorphous residue with a molecular weight of988.

EXAMPLE 2

The procedure of Example 1 is repeated using 32.5 parts (0.057 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methylphenyl)-3-n-dodecylthiopropane,80 ml of ether, 7.4 ml of pyridine and 4.5 parts (0.046 mole) ofphosgene, to give the desired carbonate as an amorphous residue with amolecular weight of 1210.

EXAMPLE 3

The procedure of Example 1 is repeated using 12.5 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methylphenyl)-3-p-butylthiobutane, 40ml of abs. ether, 3.7 ml of pyridine and 2.3 parts (0.023 mole) ofphosgene, to give the desired carbonate as a white powder with amolecular weight of 877, which is the compound claimed in claim 7.

EXAMPLE 4

13.15 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiadodecane,5.35 parts (0.025 mole) of diphenyl carbonate and 0.1 part of freshlysublimed potassium tert.-butoxide are placed in an apparatus set up fordistillation. The ingredients are heated together at 120° C. undervacuum (approx. 27 mm Hg) to form a melt, and then the temperature israised slowly to 210° C. During this time, 3.1 parts distill into thereceiver flask. The reaction is complete after approx. 1 hour. Aftercooling, the solid polycarbonate is dissolved in chloroform. The solventis evaporated off to give 12.3 parts of a finely crystalline productwith a molecular weight of 2305.

EXAMPLE 5

15.8 parts (0.03 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiodecaneand 3.8 parts (0.048 mole) of dry pyridine are placed in a reactionflask equipped with a mechanical stirrer, thermometer, condenser andinlet tube. After the addition of 100 parts of anhydrous ether, phosgeneis passed slowly into the resultant solution at 35°-40° C. until 2.4parts (0.024 mole) are absorbed. The reaction mixture is stirred at roomtemperature for 16 hours under an atmosphere of nitrogen. The pyridinehydrochloride is removed by filtration and the ether evaporated to give14.1 parts of a crude product. This crude product is recrystallised fromwater-methanol (1:1) and dried in the oven at 70° C., affording 10.6parts of a white crystalline product with a molecular weight of 737.

EXAMPLE 6

To a solution of 26.3 parts (0.05 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiodecane,6.3 parts (0.08 mole) of water-free pyridine in 100 parts by volume ofdry ether are added dropwise 3 parts by volume (0.04 mole) of thionylchloride. The reaction is exothermic. The reaction mixture is stirredunder slight reflux for 4 hours and then left for 16 hours at 23° C. Thepyridine hydrochloride is filtered off and the organic phase washedseveral times with water. Drying over sodium sulphate and removal of theether gives a yellow oil which crystallises on standing at roomtemperature. Recrystallisation from methanol gives 18.5 parts of a whiteamorphous-like product which is the polysulphite (molecular weight:1845).

EXAMPLE 7

3 parts by volume (0.04 mole) of thionyl chloride are added dropwise toa solution of 19.1 parts (0.05 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-n-butane and 6.3 parts(0.08 mole) of pyridine in 100 parts by volume of dry ether. Thereaction mixture is refluxed under nitrogen for 4 hours, then cooled,and the pyridine hydrochloride carefully removed by filtration. Workingup in the usual way gives a viscous oil which solidifies on being leftovernight at room temperature. Recrystallisation from methanol gives 9.4parts of a white crystalline product which is the polysulphite(molecular weight: 1845).

EXAMPLE 8

13.15 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiododecaneand 3.2 parts (0.04 mole) of pyridine dissolved in 100 parts by volumeof dry ether are treated dropwise with 1.6 parts by volume (0.02 mole)of thiophosgene. The reaction mixture is gently refluxed for 4 hours,cooled, and the pyridine hydrochloride is filtered off. After washingwith water, the organic phase is dried and the ether evaporated to givea green coloured polythiocarbonate which is recrystallised frommethanol. Yield: 11.1 parts (molecular weight: 755).

EXAMPLE 9

To 9.55 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-butane and 3.15 parts(0.04 mole) of pyridine dissolved in 100 parts by volume of ether areadded dropwise 1.6 parts by volume (0.2 mole) of thiophosgene. Thereaction mixture is heated to 36° C. for 4 hours, cooled, and worked upas described in Example 5 to give 8.2 parts of a polycarbonate with amolecular weight of 427.

EXAMPLE 10

13.15 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiadodenceand 7.8 parts (0.025 mole) of triphenyl-phosphite together with approx.0.1 part (approx. 0.01 mole) of freshly sublimed potassiumtert.-butoxide are heated under vacuum (1 mm Hg) to 180° C. over aperiod of 2 hours. The reaction mixture melts at approx. 90° C., is thenallowed to cool, and the product is dissolved in chloroform. The solventis evaporated off to give 10.2 parts of a crude product which isrecrystallised from methanol and dried in the oven at 40° C. to yield 8parts of a white crystalline polyphosphite.

EXAMPLE 11

11.6 parts (0.02 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiahexadecane,6.1 parts (0.02 mole) of triphenylphosphite and 0.1 part of potassiumtert.-butoxide are fused together at 180° C. (18 mm Hg) for 21/2 hours.The working up is the same as described in Example 10, giving 10 partsof a white crystalline polyphosphite.

EXAMPLE 12

A mixture of 13.9 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiatetradecane,7.8 parts (0.025 mole) of triphenylphosphite, containing a catalyticamount of potassium tert.-butoxide (0.1 mole), is heated for 21/2 hoursat 90° C. Working up as described in Examples 10 and 11 give 11 parts ofa low melting polyphosphite with a molecular weight of 860.

EXAMPLE 13

A mixture of 23.5 parts (0.05 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiaoctaneand 15.5 parts (0.05 mole) of triphenylphosphite, containing 0.2 part ofpotassium tert.-butoxide, are fused together at 180° C. for 4 hours.Working up as described in Examples 10, 11 and 12 give 17 parts of acrystalline polyphosphite.

EXAMPLE 14

13.17 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiadodecaneand 8.15 parts (0.025 mole) of triphenylphosphate, in the presence of0.1 part of potassium tert.-butoxide, are heated together at 180° C. for2 hours. The solid mass is well washed with chloroform and dried, giving11.1 parts of a slightly discoloured polyphosphate.

EXAMPLE 15

13.5 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiatetradecane,8.15 parts of triphenylphosphite and 0.1 part of potassiumtert.-butoxide are fused together at 90° C. (16 mm Hg) for 11/2 hours.The temperature is raised slowly to 130° C. and the melt is stirred atthis temperature for 2 hours. Recrystallisation of the product fromchloroform gives 11.3 parts of polyphosphate as a white crystallinesolid with a molecular weight of 2.345.

EXAMPLE 16

10.5 parts (0.02 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiadodecane,3.2 parts (0.01 mole) of triphenylphosphate and 0.1 part of potassiumtert.-butoxide are heated together for 21/2 hours at 175° C. Working upas described in Example 14 gives 7.2 parts of a polyphosphate as apowder-like substance.

EXAMPLE 17

Fusion of 13.9 parts of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiatetradecane,5.35 parts of diphenyl carbonate and 0.1 part of potassiumtert.-butoxide under vacuum (20 mm Hg) for 41/2 hours and working up asdescribed in Example 4 give 11.9 parts of a polycarbonate as a whitecrystalline solid with a molecular weight of 665.

EXAMPLE 18

1.43 parts by volume (0.02 mole) of thionyl chloride are added dropwiseat 24° C. to a solution of 13.9 parts (0.025 mole) of1,1-bis-(3-tert.-butyl-4-hydroxy-6-methyl-phenyl)-3-methyl-4-thiatetradecanein 150 parts by volume of ether containing 3.2 parts by volume (0.04mole) of pyridine. The reaction mixture is then refluxed for 4 hours andworked up as described in Examples 6 and 7 to give 9.1 parts of a whitecrystalline polysulphite with a molecular weight of 932.

EXAMPLE 19

100 parts of polypropylene (melt index 3.2 g/10 mins., 230° C./2160 g)are thoroughly mixed for 10 minutes in a shaking apparatus with 0.2 partof one of the additives listed in the following Table.

The resulting mixture is kneaded for 10 minutes at 200° C. in aBrabender plastograph and the composition thus obtained is subsequentlypressed to 1 mm thick sheets in a day-light press at a temperature of260° C. Strips 1 cm wide and 17 cm long are punched from these sheets.

The test of the effectiveness of the additive incorporated in the teststrips is carried out by means of oven ageing in a forced draught ovenat 135° C. and 149° C., a test strip which contains no additive servingas comparison. Three test strips of each formulation are used for thispurpose. The end point is defined as the onset of the slightly visibledecomposition of the test strip.

                  Table                                                           ______________________________________                                        Stabiliser No. of days until beginning of decomp.                             Example    149°    135°                                         ______________________________________                                        None        1              3                                                  1          29             76                                                  2           9             47                                                  3          43             85                                                  4          26             54                                                  5          29             66                                                  6          24             54                                                  7          23             73                                                  10         25             55                                                  11         19             57                                                  17         27             64                                                  18         25             54                                                  Comparison*                                                                               1              9                                                  ______________________________________                                         *Product of Example VB, U.S. Pat. specification 3,655,718.               

I claim:
 1. A phenol of the formula I ##STR5## wherein n has a valuefrom 1 to 15,each of R₁, R₂, R₃ and R₄ independently is a hydrogen atom,a C₁ -C₁₈ -alkyl group, an aryl group, a C₅ -C₁₂ -cycloalkyl group or aC₇ -C₁₃ -aralkyl group, R₅ is a hydrogen atom or a C₁ -C₁₈ -alkyl group,Y is carbonyl, and R₆ is a radical --CHR₈ --CHR₉ --S--CR₁₀ R₁₁ R₁₂,wherein each of R₈ and R₉ independently is a hydrogen atom or a C₁ -C₆-alkyl group, R₁₀ is a hydrogen atom, a C₁ -C₁₉ -alkyl group, a C₂ -C₄-alkenyl group or an aryl group, R₁₁ is a hydrogen atom or a methylgroup and R₁₂ is a hydrogen atom or a methyl group, or, R₁₁ is ahydrogen atom and R₁₂ is a C₂ -C₆ -alkyl group, or, R₁₀ is a hydrogenatom and R₁₁ and R₁₂ together with the carbon atom to which they areattached represent a cycloalkyl group, or R₁₀, R₁₁ and R₁₂ together withthe carbon atom to which they are attached represent an aryl group.
 2. Aphenol according to claim 1, whereinn is 1 to 4, R₁ is a hydrogen atomor a methyl group, R₂ is a hydrogen atom, a methyl, ethyl or tert.-butylgroup, R₃ is a hydrogen atom, a methyl, ethyl or tert.-butyl group, eachof R₄ and R₅ is a hydrogen atom, Y is carbonyl, R₆ is a radical --CHR₈--CHR₉ --S--CR₁₀ R₁₁ R₁₂, R₈ is a hydrogen atom, R₉ is a hydrogen atomor a methyl group, R₁₀ is a C₄ -C₁₉ -n-alkyl group, and each of R₁₁ andR₁₂ is a hydrogen atom.
 3. A phenol according to claim 1, whereinn is 1to 4, R₁ is a hydrogen atom or a methyl group, R₂ is a hydrogen atom, amethyl, ethyl, or tert.-butyl group, R₃ is a hydrogen atom, a methyl,ethyl, or tert.-butyl group, each of R₄ and R₅ is a hydrogen atom, Y iscarbonyl, R₆ is a radical --CHR₈ --CHR₉ --S--CR₁₀ R₁₁ R₁₂, R₈ is ahydrogen atom, R₉ is a hydrogen atom or a methyl group, R₁₀ is a C₄ -C₁₈-n-alkyl or phenyl group, each of R₁₁ and R₁₂ is a hydrogen atom.
 4. Aphenol according to claim 1, whereinn is 1 or 4, R₁ is a methyl group,each of R₂, R₄ and R₅ is a hydrogen atom, R₃ is a tert.-butyl group, Yis carbonyl, R₆ is a radical --CH₂ -CHR₉ --S--CH₂ R₁₀, R₉ is a methylgroup, and R₁₀ is a C₄ -C₁₂ -n-alkyl group.
 5. A phenol according toclaim 1, whereinR₁ is a methyl group, each of R₂, R₄ and R₅ is ahydrogen atom, R₃ is a tert.-butyl group, and Y is a carbonyl group. 6.An organic material which contains a compound according to claim 1 in anamount sufficient to stabilize the organic material against oxidation.7. A stabilized organic material according to claim 6 wherein theorganic material is an organic polymer.
 8. A stabilized organic materialaccording to claim 7 wherein the organic polymer is a polyolefin.
 9. Astabilized organic material according to claim 8, wherein the polyolefinis polypropylene.
 10. A process for stabilizing organic material againstoxidation which comprises incorporating thereinto a compound accordingto claim 1.